Pounds to Grams – not always straight forward in textiles

Converting weight from one country’s system to another, especially for those of us with military experience in Europe jumps right to converting miles to kilometers where we know its about 1 mile to 1.6 KM – or next converting the price of fuel between gallons and liters? However, when we start talking about weight and working between the United States supply chain (with a few exceptions where companies continue to quote prices in meters and not yards!) we have to convert fabric weight from ounces per square yard to ounces per square meter (lets not get into denier and dtex!).

So why is this important? In the world of military personal protection, there are numerous measurable factors that when combines add up to some notion of comfort and performance. Comfort translates into mission performance and staying focuses. At the crux of the issue is human performance and this really means managing the human core physiology. The amount of weight a soldier carriers is a key component to how well the core performs and for how long. Weight can also impact how durable a textile material remains although the textile composition may be more important. How a fabric is constructed will also impact how well that material holds up. construction also impacts how air permeates through the fabric which enables the process of moisture evaporation and cooling of the core. Again, a more air permeable fabric may have tradeoffs with a less permeable fabric – but we stray. We are talking about weight.

In many areas of human endeavor achieving the same or better performance with less weight is usually a good thing and so it is with combat uniforms (to a point). So we need to know how to communicate current weight as accepted by US Military Specifications into a scale that international militaries can understand and use – enter grams per square meter.

The formula is pretty strain forward – one ounce is equal to one sixteenth of a pound or 16 drams or 28.349 grams. WAIT – don’t use that formula! While a great formula for cooking recipes and drug measurements, it wont work for textiles because we have to consider the meter and yard lengths.

The answer is 1 gram = 0.03527 ounces. The textile geniuses assume we are converting between ounce-force/square yard and gram-force/square meter. The derived unit for pressure is the pascal. 1 pascal is equal to 3.00750253989 ounces per (square yard), or 101.971621298 grams per (square meter). The super smart people at http://www.ginifab.com/feeds/ozyd2_gm2/ helped me out with an example.

Question : If a fabric is 5.5oz/sq yard, how much is the weight in grams/sq meter ?
Answer : 5.5 oz/sqyd x 33.906 = 186.483 gm/sqm

And the mystery of converting ounces per square yard to grams per square meter is solved!